The present invention relates to a process for the desulfurization of light oils. More particularly, this invention relates to a process wherein light oils are irradiated with ultraviolet rays to decompose mercaptans and sulfides contained in the light oils into water-soluble compounds such as SO.sub.2, SO.sub.3 and sulfonic acids and thereafter, the irradiated light oils are washed with water to remove such water-soluble compounds.
At present, the hydrogenating desulfurization method or the sweetening method is widely adopted for refining light oils such as naphtha and staight-run gasoline. However, the hydrogenating desulfurization method is not only expensive due to the necessity for special equipment, but is also subject to operating difficulties as the method often permits occurrence of fouling and clogging of pipes with scale. On the other hand, the sweetening method, which is not suitable for complete removal of tertiary mercaptans and sulfides, is inferior in the overall desulfurization rate and has an additional disadvantage that the treated effluent from a plant using this method emits very unpleasant odors. These two methods now in practice therefor still involve some problems to be solved. Thus, there is a real demand in the field of petrochemistry for the development of a new method desulfurizing light oils completely by a simple operation without the necessity of special equipment.